[ch-087/jeongoon] Haskell Task #1

1 files changed, 32 insertions, 0 deletions

diff --git a/challenge-087/jeongoon/haskell/ch-1.hs b/challenge-087/jeongoon/haskell/ch-1.hs
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+++ b/challenge-087/jeongoon/haskell/ch-1.hs
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+import System.Environment
+import System.Exit
+import Data.Char (isNumber)
+import Data.Maybe (catMaybes)
+import Data.List (sort, sortBy)
+
+{- tested with: runhaskell ch-1.hs  1 3 2 -1 -2 -3 6 7 9 1
+(only shows one answer)
+-}
+
+
+answerLongestConsecutiveSequence :: [Int] -> [Int]
+answerLongestConsecutiveSequence =
+  ( head
+  . sortBy (\a b -> (length b) `compare` (length a))
+  . consecutiveSequences )
+
+  where
+    consecutiveSequences =
+      ( scanl1 (\a b -> if (head b)-(last a) == 1 then (a++b) else b)
+        . map (:[])
+        . sort )
+
+main = do
+    (catMaybes.map (\nStr ->
+                       if (all isNumber nStr) then Just(read nStr :: Int)
+                       else Nothing )) `fmap` getArgs
+      >>= (\nums ->
+              if length nums < 1 then
+                die "Usage: runhaskell ch-1.hs <integer> ..."
+              else
+                putStrLn $ show ( answerLongestConsecutiveSequence nums ) )